High voltage contactor



C. A. LISTER HIGH VOLTAGE CONTACTOR Jan. 16, 1962 2 Sheets-Sheet 1 Filed April 25, 1958 Inventor (HARLEJ 4. 0:72-7

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HIGH VOLTAGE CONTACTOR Filed April 25, 1958 2 Sheets-$heet 2 Z'moentor (/M ELEJ' ,4. dun-2,

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United States Patent a 3,017,481 HIGH VOLTAGE CONTACTOR Charles A. Lister, Shaker Heights, Ohio, assignor to Square D Company, Detroit, Mich, a corporation of Michigan Filed Apr. 25, 1958, Ser. No. 730,867 5 Claims. (Q1. 200147) The present invention relates to contactors and more particularly to high voltage alternating current, air-break contactors having the terminals for connection of outgoing or load leads connected to the front side of the contactor.

Air-break contactors capable of interrupting alternating current circuits under fault conditions have been constructed in the past with both incoming or source leads and outgoing or load leads connected to terminals at the back of or away from the front of the contactor. Such a contactor is illustrated and described in Patent No. 2,790,878, issued April 30, 1957 for interrupting currents when the available three phase short circuit capacity of the circuits is as high as 50,000 kva. and the voltages are within the range of 2000 and 6000 volts. In these prior contactors, the outgoing leads are connected to the assembly at a distance from the front of the contactor and usually at the bottom on the back side of the contactor. Because these contactors are large, the bottom back side of the contactor is out of convenient reach of workmen trying to either reach over the top of or around the side of the contactor after it is mounted in cabinets or locations where there is insufficient working space both in front of and in back of the contactor to enable workmen to easily connect all power and load leads to the contactors. Such installations are acceptable where there is ample floor space and where the contactors can be mounted sufficiently away from a stationary wall to permit a workman to-conveniently make his connections on the back side of the contactor.

Generally incoming or source leads are secured and connected to the line terminals in the factory or during installation of the contactor in the cabinet and do not have to be disconnected after the contactor has been installed. Also, the line terminals, being near the top of the contactor, are accessible and can be reached if necessary from the front. On the other hand, the load leads are not connected to the load terminals until the contactor is in position for use. Occasionally, it is necessary to connect and disconnect the load leads in order to use one contactor for various loads. It is apparent that such load connections are easier to make and remove it the load terminals are at a place which can be safely and conveniently reached by workmen. Workmen can safely reach the front of the contactor when it is not accessible directly from the back of the cabinet. Further, when the load terminals are placed on the front of the contactor it is unnecessary to provide working space at the rear of the contactor.

The requirement for working space only in front of the contactor and the elimination of the need of working space behind the contactor results in a saving of up to one half of the original floor space needed to make connections. This savings is obtained since the cabinet may be positioned against a wall, instead of being set away from the wall as was previously done. Also, if the contactor is mounted on large equipment such as bridges etc., the supporting structure and flooring may be lighter since the bending moments or forces from the weight of the cabinet and contactor are greatly reduced by placing them against the wall instead of out away therefrom.

The present invention further permits use of a more economical cabinet by eliminating the need for a re- 3,017,481 Patented Jan. 16, 1962 movable back or a door on the back of the cabinet. With the present contactor load connections can easily be made or changed safely and conveniently from the front side even after the contactor has been installed.

In order to provide the contactor with terminals for outgoing or load leads on the front, the anti-blowofl and movable contact lead assembly of the contactor must be designed differently from those used in prior back-connected contactors. It is desirable, however, that this assembly should include parts interchangeable with those of the prior anti-blowoff and movable contact lead as semblies of back-connected contactors.

The present invention overcomes the problems of maintaining balanced electrical, mechanical, and magnetic forces in air-break contactors when interrupting fault currents at voltages of 2000 to 6000 volts in circutis having an available capacity of 50,000 kva. or higher. At these high voltage and kva. capacities magnetic fields established by current flowing through the contacts and the movable contact lead assembly must be balanced or counteracted so that they do not tend to urge the contacts apart.

It is apparent that one of the objects of the present invention is to overcome the aforementioned problems and others.

Another object of the present invention is to provide an improved air-break contactor of high interrupting capacity having at least the load terminals on the front.

A further object of the present invention is to provide an improved anti-blowoff and movable contact lead as sembly for a front-connected contactor.

A further object of the invention is to provide an antiblowoif and movable contact lead assembly for a front connected contactor which is efficient in operation, easy to maintain, economical to construct, and is effective to neutralize the magnetic forces caused by currents flowing through the contactor.

Other objects and a fuller understanding of the inven tion will become apparent from the following description of an embodiment of the invention, taken in conjunction with the claims and the attached drawings in which:

FIG. 1 is a side view of a contactor mounted in a cabinet, partly in section, illustrating the features of the invention; and

FIG. 2 is a partial front view of the contactor of FIG. 1.

Referring to the drawings which illustrate one embodiment of the invention as an example, a contactor frame 10 has mounted on the back side thereof a back panel 11 of insulating material which supports a blowout and sta tionary power contact assembly 12 including a stationary contact 13 at the front end of a contact stud 13a. An operating shaft 14 extends across the lower portion of the frame 10 and supports a movable power contact assembly 15 including a movable contact 16 which is movable towards and away from the stationary contact 13 in a path defined laterally by generally upright parallel planes. in this instance the path is an arcuate path having its center at the pivot axis of the shaft '14. An antiblowoif assembly 17 is mounted in horizontally spaced relation on the frame 10 and in front of the shaft 14 and is associated with the movable power contact assembly 15. The contactor further includes an arc chute 18 provided with front and back runners 19 and 20 in such manner that the arc runners are in cooperative relationship with their respective contacts 13 and 16. The frame 10, panel 11, the blowout and stationary power contact assembly 12, the operating shaft 14, the movable power contact assembly 15, and the arc chute 18 are each preferably constructed in accordance with the description and illustration of the similar parts in the hereinbefore mentioned Patent No. 2,790,878 and therefore will not be further detailed herein.

The anti-blowoff assembly 17 in accordance with this invention comprises a stand-off insulator 21 mounted on the front of frame and a metal post or pedestal 22 mounted on top of the insulator 21 and constituting a rigid conductor. The pedestal 22 is, in this instance, constructed from a single piece of material and has at its lower end portion 22 a rearwardly directed and downwardly inclined tongue portion 23 terminating in a free end 23a to which a flexible connector 24 is attached. The pedestal 22 has at its upper end portion 2% a spring clip 25 engageable with front are runner 19. The pedestal 22 also has a forwardly extending terminal portion 26 disposed above lower end portion 22a and below upper end portion 22b and to which an outgoing or load lead, such as a lead 27, may be bolted or otherwise fastened. It is to be noted that the terminal portion 26 is at a substantial distance from free end 23a and is in front of the contactor so that it is readily accessible to workmen from the front side of the contactor. The tongue portion 23 and the terminal portion 2a of the pedestal 22 are interjoined by a strengthening or reinforc ing web 220 which cooperates therewith to provide a modified arcuate or a modified quarter circular shaped rigid conductor.

Current is transmitted between contact 16 and termi nal 26 by the pedestal 22 and the flexible connector 24 which, in the described embodiment, is of modified arcuate or modified semi-circular shape. One end of the flexible connector 24 is attached to movable contact 16 and the other end is attached to free end 23:; of tongue portion 23. Thus the flexible connector 24 and the rigid conductor or pedestal 22 are joined at a common end thereof. It is also noted that the flexible connector 24 and the rigid conductor 22 including the tongue portion 23 are disposed generally in a plane which is aligned with the path of movement of the movable contacts 16 and that the flexible connector is between the rigid conductor 22 and the movable contact 16. Thus the path of movement of the movable contact 16 is positioned between the stationary contact 13 and the rigid conductor or pedestal 22.

When a contactor of the type described is used in an alternating current circuit of large availabl short circuit capacity, fault currents create large electromagnetic forces. The electromagnetic forces set up by such currents flowing through the contacts 213 and 16 and through the flexible connector 24 tend to expand a first loop thus formed by straightening the modified arcuate shaped flexible connector 24 and forcing the connector 24 forwardly, thereby to cause premature opening of the contacts 13 and 16. These forces of expansion or straightening of connector 24 are neutralized in the present construction by the anti-blowoif assembly 17 just described. This is because at least a portion of the flexible connector 24 and rigid conductor 22, including tongue 23, forms a second loop, the forces of which oppose the forces of the first loop and tend to force the connector 24 rearwardly toward the base 11. Consequently, the forces tending to move the connector 24 forwardly are substantially neutralized and there is insuflicient resultant force to separate the contacts 13 and 16 when normal or fault currents flow through the contactor.

FIG. 1 further illustrates the contactor as being mounted in a cabinet C to better show the accessibility of the load terminal connection obtained by placing the load terminal in front of the contactor in accordance with the present invention. It is apparent that terminal connection 26, being on the front, is readily accessible to workmen, whereas the lower back side (area C in FIG. 1) is relatively inaccessible, especially when the contactor is of the 50,000 kva. capacity, from the front of the cabinet.

Such contactors are large enough (usually over 30" high) to put area C out of convenient reach of workmen having access only to the front of the contactor.

The specific example herein described sets forth one embodiment incorporating the objects and advantages of the present invention. It i understood that various modifications in the details of the structure and arrangement of parts may be had without departing from the spirit and scope of the following claims.

Having thus described my invention, I claim:

1. In a contactor having a stationary contact and a movable contact and means for moving said movable contact in a path towards and away from the stationary contact, the provision of a current conductive pedestal having upper and lower end portions and a terminal portion between said end portions and providing a terminal for connection to a load, a tongue joined to said lower end portion and extending downwardly and rearwardiy therefrom, and a modified arcuate shaped flexible connector connected at one end to the lower end of said tongue and at the other end to said movable contact, said connector, pedestal and tongue being disposed in a plane common to the plane of the path of movement of the movable contact with the flexible connector also disposed between the movable contact and the pedestal, said flexible connector defining a first current conductive loop, said terminal portion being spaced from said tongue and defining a conducting path of substantial length in said lower portion of said pedestal, which conducting path, together with said tongue, defines a second current conductive loop in series with and in force opposition to said first loop whereby flow of current through both loops produces forces in the second loop in neutralizing force opposition to the forces in the first loop, and said flexible connector from its point of connection with the tongue being spaced rearwardly from the pedestal and tongue along the entire length of the adjacent portions of the pedestal and tongue.

2. The structure of claim 1 including a reinforcing web interconnecting said terminal portion with said tongue and said lower end portion of said pedestal and having a rearwardly disposed arcuate edge extending closely alongside of, and spaced forwardly of, the forward surface of the flexible connector.

3. In a contactor for alternating current systems comprising a stationary contact, a first conductor means connected to, and extending rearwardly of the contactor from, the stationary contact, a movable contact engageable with the stationary contact and movable to an open circuit position in a direction forwardly of the stationary contact in a path defined laterally by generally upright parallel planes, an insulating pedestal support, a generally upwardly extending conductive pedestal mounted on said support and spaced forwardly fro-m the movable contact and in alignment generally with the path thereof, said pedestal having a lower rearward extension and a terminal portion with a terminal on its forward face disposed above said rearward extension, said terminal portion defining a conducting path of substantial length in said pedestal between said terminal and said rearward extension, a flexible connector electrically connected at one end to said lower rearward extension and at the other end to said movable contact, said flexible connector, throughout a substantial portion of its length, being above and aligned with said lower rearward extension and disposed at all times rearwardly from and closely adjacent to said conducting path in said pedestal, a second conductor means connected to said pedestal at said terminal portion, whereby two conducting loops, which are in series with each other, are formed and one of said loops includes said first conductor means, said stationary and movable contacts, and at least a portion of said flexible connector, and the other of said loops includes the portion of said pedestal below said terminal portion, said rearward extension, and at least a portion of said flexible connector, and the spacing of said loops being such that repulsive forces, produced by a current flowing in the loops, are in opposition to each other and of such relative magnitude that the flexible connector is urged in said direction for closing the contacts.

4. The contactor of claim 3 characterized in that said pedestal has an upper portion extending upwardly from said terminal portion, an arc runner for the movable contact has a portion disposed in arc-receiving position with respect to said movable contact, inter-engageable fastening means are provided on said are runner and on said upper portion of said pedestal, respectively, for securing References Cited in the file of this patent UNITED STATES PATENTS 2,790,878 Lister Apr. 30, 1957 

